Clin Should Elbow.  2021 Sep;24(3):141-146. 10.5397/cise.2021.00213.

Scapular spine base fracture with long outside-in superior or posterior screws with reverse shoulder arthroplasty

• Eroğlu ON
• Hüsemoğlu B
• Başçı O
• Özkan M
• Havıtçıoğlu H
• Hapa O

• KMID: 2520008
• DOI: http://doi.org/10.5397/cise.2021.00213

Abstract

Background
The purpose of the present study was to determine how long superior screws alone or in combination with posterior placement of metaglene screws protruding and penetrating into the scapular spine in reverse total shoulder arthroplasty affect the strength of the scapular spine in a fresh cadaveric scapular model.
Methods
Seven fresh cadaver scapulas were allocated to the control group (short posterior and superior screws) and seven scapulars to the study group (spine base fixation with a four long screws, three with both long superior and long posterior screws).
Results
The failure load was lower in the spine fixation group (long screw, 869 N vs. short screw, 1,123 N); however, this difference did not reach statistical significance (p>0.05). All outside-in long superior or superior plus posterior screws failed due to scapular spine base fracture; failures in the short screw group were due to acromion fracture. An additional posterior outside-in screw failed to significantly decrease the failure load of the acromion spine.
Conclusions
The present study highlights the significance of preventing a cortical breach or an outside-in configuration when a superior or posterior screw is inserted into the scapular spine base.

Keyword

Reverse shoulder arthroplasty; Biomechanical testing; Acromion fracture